Relationships between Environmental Conditions and Production-and Consumption Activities of Individual Leaves in the Population of Rice Plant in a Paddy Field : IV. Leaf positional and seasonal cahnges in the rates of net photosynthesis and dark respiration in paddy fields of different plant spacing and fertilization

Gas exchange of jointed goatgrass leaves was affected by temperature, irradiance level, and soil matric potential. Net photosynthesis of leaves under saturating irradiance (PPFD3= 1850 (μE·m–2·s−1) was optimum at about 20 C. At 25 C, net photosynthesis was nearly 90% of maximum at a PPFD of 800 μE·m–2·−1. Transpiration, and presumably water use, increased steadily with temperature from 10 to 40 C. Dark respiration rate and compensation points for light and for CO2increased exponentially, or nearly so, from 10 to 40 C. Soil moisture deficits of −130 kPa reduced net photosynthesis and transpiration by about 30 and 55%, respectively, compared to well-watered plants.

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Assessment of a three-stage sampling strategy to investigate the spatial distribution and population density of Aphelenchoides besseyi among Oryza sativa seeds

Nematology ◽

10.1163/138855409x12549869072284 ◽

2010 ◽

Vol 12 (3) ◽

pp. 373-380

Author(s):

Katsumi Togashi ◽

Shigeru Hoshino

Keyword(s):

Spatial Distribution ◽

Oryza Sativa ◽

Paddy Field ◽

Rice Plant ◽

Spatial Scales ◽

Sampling Strategy ◽

Paddy Fields ◽

Nematode Density ◽

Aphelenchoides Besseyi ◽

The Mean

AbstractThis study aimed to determine the spatial distribution patterns of Aphelenchoides besseyi among Oryza sativa seeds on panicle, plant hill, and paddy field spatial scales and to present a three-stage sampling method for estimating the mean density per seed in paddy fields. Living and dead nematodes were extracted individually from 20 seeds sampled from each of five panicles, which were sampled from each of six rice plant hills in each of eight paddy fields, where all plants had leaves exhibiting the 'white tip' symptom. Nested ANOVA indicated that A. besseyi density per seed was significantly different among the eight paddy fields, among rice plant hills in paddy fields, and among panicles in rice plant hills. The proportion of nematode-infested seeds (prevalence) increased and reached an upper limit as the mean density per seed on the panicle scale increased, whereas linear relationships were observed between nematode prevalence and the mean density on plant hill and paddy field scales. Relationships between mean density and mean crowding of nematodes per seed indicated that the nematodes exhibited clumped distribution on each of panicle, plant hill and field scales. Using these relationships, a three-stage sampling plan for estimating nematode density per seed at a specified precision level is presented.

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The Fate of Fertilizer Nitrogen Applied to the Paddy Field and its Absorption by Rice Plant : VIII. Comparative studies of the fate of basal nitrogen and the absorption of nitrogen by rice plant in different paddy fields

Japanese Journal of Crop Science ◽

10.1626/jcs.45.226 ◽

1976 ◽

Vol 45 (2) ◽

pp. 226-231 ◽

Cited By ~ 4

Author(s):

Sadao SHOJI ◽

Teruo NOGI ◽

Juro TAKAHASHI ◽

Genshichi WADA

Keyword(s):

Paddy Field ◽

Comparative Studies ◽

Rice Plant ◽

Paddy Fields ◽

Fertilizer Nitrogen

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The Value of a Decrease in Temperature by One Degree Celsius of the Regional Microclimate—The Cooling Effect of the Paddy Field

Atmosphere ◽

10.3390/atmos12030353 ◽

2021 ◽

Vol 12 (3) ◽

pp. 353

Author(s):

Ya-Wen Chiueh ◽

Chih-Hung Tan ◽

Hsiang-Yi Hsu

Keyword(s):

Land Use ◽

Surface Temperature ◽

Paddy Field ◽

Research Area ◽

Paddy Fields ◽

Cooling Effect ◽

Field Temperature ◽

Bare Land ◽

The Face ◽

The Difference

In the face of climate change, extreme climates are becoming more frequent. There were severe droughts in Taiwan in 2020, 2014–2015, and 2002. In these years, the paddy fields were kept fallow to save water and transfer agricultural water to non-agricultural use. On the other hand, with global warming, the existence of paddy fields may be one of the natural solutions to regional temperature mitigation. This study used remote sensing to quantify the difference in temperature between paddy fields and urban areas. The result of overall surface temperature deductive analysis revealed that the temperature in the whole Taoyuan research area was 1.2 °C higher in 2002 than in 2003 because of fallowing of the paddy field, while in the Hsinchu research area, it was 1.5 °C higher in 2002 than in 2003, due to the same reason described above. In terms of the difference in land use, for the Hsinchu research area, the surface temperature deductive result showed that the average paddy field temperature in 2002 was 22.3 °C (sample area average), which was 7.7 °C lower than that of the building and road point and 4.3 °C lower than that of the bare land point. The average paddy field temperature in 2003 was 19.2 °C (sample area average), which was 10.1 °C lower than that of the building and road point and 8.3 °C lower than that of the bare land point. Then this study evaluated the economic valuation of the paddy field cooling effect using the contingent valuation method. Through the paddy field cooling effect and in the face of worsening extreme global climate, the willingness to pay (WTP) of the respondents in Taiwan for a decrease of 1 °C with regard to the regional microclimate was evaluated. It was found that people in Taiwan are willing to pay an extra 8.89 USD/per kg rice/year for the paddy for a decrease in temperature by 1 °C in the regional microclimate due to the paddy field. Furthermore, this study applied the benefits transfer method to evaluate the value of a decrease of 1 °C in the regional microclimate in Taiwan. The value of a decrease of 1 °C in the regional microclimate in Taiwan is 9,693,144,279 USD/year. In this regard, the economic value of 1 °C must not be underestimated. In conclusion, more caution is needed while making decisions to change the land use of paddy fields to other land uses.

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Effects of Contemporary Land Use Types and Conversions from Wetland to Paddy Field or Dry Land on Soil Organic Carbon Fractions

Sustainability ◽

10.3390/su12052094 ◽

2020 ◽

Vol 12 (5) ◽

pp. 2094

Author(s):

Di Zhao ◽

Junyu Dong ◽

Shuping Ji ◽

Miansong Huang ◽

Quan Quan ◽

...

Keyword(s):

Land Use ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Constructed Wetland ◽

Paddy Field ◽

Heavy Fraction ◽

Light Fraction ◽

Paddy Fields ◽

Dry Land ◽

Natural Wetlands

Soil organic carbon (SOC) concentration is closely related to soil quality and climate change. The objectives of this study were to estimate the effects of contemporary land use on SOC concentrations at 0–20 cm depths, and to investigate the dynamics of SOC in paddy-field soil and dry-land soil after their conversion from natural wetlands (20 and 30 years ago). We investigated the dissolved organic carbon (DOC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), and other soil properties (i.e., moisture content, bulk density, pH, clay, sand, silt, available phosphorous, light fraction nitrogen, and heavy fraction nitrogen) in natural wetlands, constructed wetlands, fishponds, paddy fields, and soybean fields. The results indicated that the content of DOC increased 17% in constructed wetland and decreased 39% in fishponds, and the content of HFOC in constructed wetland and fishponds increased 50% and 8%, respectively, compared with that in natural wetlands at 0–20 cm. After the conversion of a wetland, the content of HFOC increased 72% in the paddy fields and decreased 62% in the dry land, while the content of DOC and LFOC decreased in both types. In the paddy fields, LFOC and HFOC content in the topmost 0.2 m of the soil layer was significantly higher compared to the layer below (from 0.2 to 0.6 m), and there were no significant differences observed in the dry land. The findings suggest that the paddy fields can sequester organic carbon through the accumulation of HFOC. However, the HFOC content decreased 22% after 10 years of cultivation with the decrease of clay content, indicating that paddy fields need to favor clay accumulation for the purpose of enhancing carbon sequestration in the paddy fields.

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Cultivation of rice for animal feed with circulated irrigation of treated municipal wastewater for enhanced nitrogen removal: comparison of cultivation systems feeding irrigation water upward and downward

Water Science & Technology ◽

10.2166/wst.2015.251 ◽

2015 ◽

Vol 72 (4) ◽

pp. 579-584 ◽

Cited By ~ 7

Author(s):

A. Muramatsu ◽

H. Ito ◽

A. Sasaki ◽

A. Kajihara ◽

T. Watanabe

Keyword(s):

Nitrogen Removal ◽

Irrigation Water ◽

Rice Plant ◽

Municipal Wastewater ◽

Animal Feed ◽

Paddy Fields ◽

Treated Wastewater ◽

Human Consumption ◽

Cultivation System ◽

Treated Municipal Wastewater

To achieve enhanced nitrogen removal, we modified a cultivation system with circulated irrigation of treated municipal wastewater by using rice for animal feed instead of human consumption. The performance of this modified system was evaluated through a bench-scale experiment by comparing the direction of circulated irrigation (i.e. passing through paddy soil upward and downward). The modified system achieved more than three times higher nitrogen removal (3.2 g) than the system in which rice for human consumption was cultivated. The removal efficiency was higher than 99.5%, regardless of the direction of circulated irrigation. Nitrogen in the treated municipal wastewater was adsorbed by the rice plant in this cultivation system as effectively as chemical fertilizer used in normal paddy fields. Circulated irrigation increased the nitrogen released to the atmosphere, probably due to enhanced denitrification. Neither the circulation of irrigation water nor its direction affected the growth of the rice plant and the yield and quality of harvested rice. The yield of rice harvested in this system did not reach the target value in normal paddy fields. To increase this yield, a larger amount of treated wastewater should be applied to the system, considering the significant amount of nitrogen released to the atmosphere.

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